JP2022189850A - Inkjet ink, and tablet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet ink capable of lowering reduction of print restarting property even when heightening drying characteristics by increasing an addition amount of an alcohol solvent in a carbon inkjet ink, and a tablet provided with a print part printed by the inkjet ink.

SOLUTION: The inkjet ink pertaining to the present embodiment includes: water; an alcohol solvent; carbon; a dispersant; and a humectant, where the alcohol solvent includes at least only one of isopropyl alcohol, and normal propyl alcohol, the concentration of the alcohol solvent is 35 pts.mass or lower to a total of the inkjet ink, the dispersant includes a sucrose fatty acid ester having an HLB value of 11 or higher and 20 or lower, the content of the sucrose fatty acid ester is in a range of 48 mass% or more and 100 mass% or less in relation to the carbon, and the humectant includes only either one of propylene glycol and glycerol.

SELECTED DRAWING: None

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to inkjet inks and tablets.

Some inks for inkjet printing (hereinafter also simply referred to as "inkjet inks") are edible. For example, JP-A-2003-100000 discloses a technique related to edible inkjet ink.
Edible inkjet inks include, for example, alcohol solvents. Edible ink-jet inks include, for example, black pigments containing carbon such as vegetable carbon powder pigments.

Japanese Patent Application Laid-Open No. 2006-169301

Inkjet inks containing carbon (hereinafter also simply referred to as "carbon inkjet inks") are sometimes required to have the ability to dry the ink after printing, that is, so-called dryness. As a method for improving this performance, for example, there is a method of adding a highly drying alcohol solvent to the inkjet ink and increasing the amount of the alcohol solvent added. However, this method may deteriorate the resumability of printing. Note that the aforementioned print resumability is also called intermittent print resumability.

On the other hand, when printing is performed using a carbon inkjet ink in which the amount of the alcohol solvent added is reduced, although the resumability of printing is improved, for example, the drying property of the ink tends to be deteriorated. For this reason, using an inkjet ink with a reduced amount of alcohol solvent added, for example, when characters are printed on tablets with low drying properties such as film-coated tablets (FC tablets) and sugar-coated tablets, the low drying properties of the ink As a result, there is a risk that the ink may be transferred to printing press members or other tablets.

The present invention has been made in view of the above circumstances, and even when the amount of alcohol solvent added to the carbon inkjet ink is increased to improve the drying property, it is possible to reduce the deterioration of the resumability of printing. It is an object of the present invention to provide an inkjet ink that can be used and a tablet provided with a printed portion printed with the inkjet ink.

An inkjet ink according to an aspect of the present invention is an inkjet ink containing water, an alcohol solvent, carbon, and a dispersant, wherein the inkjet ink further contains a wetting agent, and the alcohol solvent is isopropyl alcohol. and normal propyl alcohol, the concentration of the alcohol solvent is 35 parts by mass or less with respect to the entire inkjet ink, and the dispersant has an HLB value in the range of 11 or more and 20 or less. Contains a sugar fatty acid ester, the content of the sucrose fatty acid ester is in the range of 48% by mass or more and 100% by mass or less with respect to the carbon, and the wetting agent contains only one of propylene glycol and glycerin include.

According to one aspect of the present invention, even when the amount of the alcohol solvent added to the carbon inkjet ink is increased to improve the drying property, it is possible to reduce the decrease in resumability of printing.

1A and 1B are a plan view and a cross-sectional view showing a first configuration example of a medical tablet according to the present embodiment; FIG. FIG. 4A is a plan view and a cross-sectional view showing a second configuration example of the medical tablet according to the present embodiment;

An inkjet ink according to an embodiment of the present invention relates to, for example, an inkjet ink used when printing characters, images, etc. on the surface of a medical tablet by an inkjet printing method. Hereinafter, the inkjet ink according to the embodiment of the present invention and the configuration of a tablet having a printed portion printed with the inkjet ink will be described in detail.

[Composition of inkjet ink]
The inkjet ink according to this embodiment contains at least water, an alcohol solvent, carbon, and a dispersant. The alcohol solvent according to this embodiment contains at least one of isopropyl alcohol (IPA) and normal propyl alcohol (NPA), and its content (concentration) is 35 parts by mass or less relative to the entire inkjet ink. In addition, the dispersant according to the present embodiment contains a sucrose fatty acid ester having an HLB value within the range of 11 or more and 20 or less, and the content thereof is 48% by mass or more and 100% by mass with respect to the carbon contained in the inkjet ink. % or less. With such a configuration, even when the amount of the alcohol solvent added to the carbon inkjet ink is increased to improve the drying property, it is possible to reduce the decrease in resumability of printing. The details of each component will be described below.

(carbon)
The carbon contained in the inkjet ink according to the present embodiment is not particularly limited. origin of carbon black. Among these carbons, those that can be orally ingested are particularly preferable. When orally ingestible carbon is used, the inkjet ink according to the present embodiment can be used for direct printing on tablet surfaces, direct printing on food, and packaging for direct contact with pharmaceuticals and food.
The inkjet ink according to the present embodiment may appropriately contain a pigment that can be orally ingested in order to adjust the color of the ink, in addition to the carbon as the black pigment. As the orally ingestible colorant, for example, known synthetic food colorants and natural food colorants are appropriately selected and used as food colorants.

Synthetic food colorings include, for example, tar colorings, natural coloring matter derivatives, natural synthetic coloring matter, and the like. Examples of tar pigments include Food Red No. 2, Food Red No. 40, Food Red No. 102, Food Red No. 104, Food Red No. 105, Food Red No. 106, Food Yellow No. 4, Food Yellow No. 5 and Food Blue. Food Blue No. 2, Food Red No. 2 Aluminum Lake, Food Red No. 3 Aluminum Lake, Food Red No. 40 Aluminum Lake, Food Yellow No. 4 Aluminum Lake, Food No. 5 Aluminum Lake, Food Blue No. 1 Aluminum Lake, Edible Blue No. 2 aluminum lake and the like can be mentioned. Examples of natural pigment derivatives include norbixin potassium and the like. Examples of natural synthetic pigments include β-carotene and riboflavin.

Examples of natural edible dyes include anthocyanin dyes, carotenoid dyes, quinone dyes, flavonoid dyes, betaine dyes, monascus dyes, and other dyes derived from natural products. Examples of anthocyanin pigments include red radish pigment, red cabbage pigment, red rice pigment, elderberry pigment, cowberry pigment, gooseberry pigment, cranberry pigment, salmonberry pigment, perilla pigment, swim blueberry pigment, strawberry pigment, and dark sweet. cherry pigment, cherry pigment, hibiscus pigment, huckleberry pigment, grape juice pigment, grape skin pigment, black currant pigment, blackberry pigment, blueberry pigment, plum pigment, whiteberry pigment, boysenberry pigment, mulberry pigment, purple sweet potato pigment , purple corn pigment, purple yam pigment, raspberry pigment, red currant pigment, loganberry pigment, and other anthocyanin pigments. Examples of carotenoid pigments include annatto pigments, gardenia yellow pigments, and other carotenoid pigments. Examples of quinone-based dyes include cochineal dyes, chikon dyes, lac dyes, and other quinone-based dyes. Examples of flavonoid pigments include safflower yellow pigment, sorghum pigment, onion pigment, and other flavonoid pigments. Examples of betaine dyes include beet red dyes. Monascus dyes include, for example, monascus dyes and monascus yellow dyes. Other pigments originating from natural products include, for example, turmeric pigments, rabbit pigments, gardenia red pigments, spirulina blue pigments, and the like.

(solvent)
The inkjet ink according to this embodiment contains a solvent for dispersing the aforementioned carbon. The solvent contains water as the main solvent and an alcohol solvent as the dry solvent. The main solvent and dry solvent are described below.
- Main solvent The main solvent contained in the inkjet ink according to the present embodiment is water, for example, purified water. In addition, the above-mentioned "main solvent" means the component with the largest mass ratio in the whole solvent. The ratio of water as the main solvent contained in the inkjet ink according to this embodiment is, for example, 50% by mass or more of the entire inkjet ink.

Dry solvent The dry solvent contained in the inkjet ink according to the present embodiment is an alcohol solvent, for example, an alcohol solvent containing at least one of isopropyl alcohol (IPA) and normal propyl alcohol (NPA). The concentration of this alcohol solvent is 35 parts by mass or less with respect to the entire inkjet ink. If the concentration of the alcohol solvent exceeds 35 parts by mass with respect to the entire inkjet ink, the ink tends to dry excessively and the resumability of printing tends to deteriorate. Also, the lower limit of the concentration of the alcohol solvent is not particularly limited, but is, for example, 0.001 parts by mass or more with respect to the entire inkjet ink. Within the above numerical range, deterioration in resumability of printing can be reduced.

(dispersant)
The inkjet ink according to the present embodiment contains a dispersant in addition to the carbon and solvent described above. The dispersant that can be added to the inkjet ink according to the present embodiment can improve the dispersibility of the carbon described above and is edible. It is a sucrose fatty acid ester. The content of the sucrose fatty acid ester is within the range of 48% by mass or more and 100% by mass or less with respect to the aforementioned carbon. If the content of the sucrose fatty acid ester, which is a dispersant, is less than 48% by mass relative to the carbon, the dispersion stability of the carbon tends to decrease. Moreover, when the content of the sucrose fatty acid ester as a dispersant exceeds 100% by mass with respect to the above-mentioned carbon, there is a tendency that the drying property is lowered.

Further, the sucrose fatty acid ester contained in the inkjet ink according to the present embodiment has an HLB (Hydrophilic-Lipophilic Balance) value within the range of 11 or more and 20 or less. With such a configuration, it is possible to impart sufficient drying properties to the inkjet ink and to reduce deterioration in resumability of printing. Incidentally, when the HLB value of the sucrose fatty acid ester is less than 11, there is a tendency for the resumability of printing to deteriorate. Moreover, the upper limit of the HLB value of sucrose fatty acid ester is 20.

(wetting agent)
The inkjet ink according to the present embodiment may contain a wetting agent in addition to the carbon, solvent, and dispersant described above, and the content thereof is 0.001 parts by mass or more and 20 parts by mass or less with respect to the entire inkjet ink. may be within the range of With such a configuration, it is possible to impart sufficient drying properties for use in inkjet inks, and to further reduce deterioration in resumability of printing. If the content of the humectant is less than 0.001 part by mass relative to the total amount of the inkjet ink, the resumability of printing tends to deteriorate. Moreover, when the content of the humectant exceeds 20 parts by mass with respect to the entire inkjet ink, it tends to be difficult to impart sufficient drying properties to the inkjet ink.

Further, in the inkjet ink according to the present embodiment, it is more preferable if the content of the wetting agent is 3 parts by mass or less with respect to the entire inkjet ink. With such a configuration, it is possible to impart sufficient drying properties to the inkjet ink, and to further reduce deterioration in resumability of printing.
Wetting agents that can be added to the inkjet ink according to the present embodiment are not particularly limited as long as they are generally added to inkjet inks as wetting agents. The wetting agent according to this embodiment is more effective if it has a high boiling point. Here, "high boiling point" means, for example, 140°C or higher.

Specific examples of the wetting agent according to this embodiment include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, pentamethylene glycol, trimethylene glycol, 2-butene-1, 4-diol, and 2-ethyl-1. , 3-hexanediol, 2-methyl-2,4-pentanediol, tripropylene glycol, polyethylene glycol having a number average molecular weight of 2000 or less, 1,3-propylene glycol, isopropylene glycol, isobutylene glycol, glycerin, mesoerythritol, penta Erythritol, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone and the like. Among these humectants, humectants containing at least one of propylene glycol and glycerin are particularly preferred. With such a configuration, it is possible to impart sufficient drying properties to the inkjet ink, and to further reduce deterioration in resumability of printing.
Moreover, the wetting agent according to the present embodiment may be used, for example, singly or in combination of two or more.

(binder)
The inkjet ink according to this embodiment may contain a binder in addition to the aforementioned carbon, solvent, dispersant, and wetting agent. The binder that can be added to the inkjet ink according to the present embodiment is not particularly limited as long as it is generally added to the inkjet ink as a binder, and includes, for example, polysaccharides. Moreover, the polysaccharide contained in the binder according to the present embodiment preferably has a weight-average molecular weight within the range of 1,000 or more and 10,000 or less. With such a configuration, it is possible to impart sufficient drying properties to the inkjet ink, and to further reduce deterioration in resumability of printing. If the weight-average molecular weight of the polysaccharide used as the binder is less than 1,000, it tends to be difficult to impart sufficient drying properties to the inkjet ink. Further, when the weight average molecular weight of the polysaccharide used as the binder exceeds 10,000, the resumability of printing tends to deteriorate.

Moreover, the content of the binder according to the present embodiment is preferably 0.01% by mass or more and 10% by mass or less of the total mass of the inkjet ink. When the content of the binder is within the above range, the viscosity of the ink is such that ink-jet printing can be suitably performed.
Examples of binders according to the present embodiment include maltodextrin, erythritol, PVP (polyvinylpyrrolidone), dextran, polydextrose, starch substances such as corn and wheat, cellulosic substances such as carboxymethylcellulose and hydroxymethylcellulose, sodium alginate, Polysaccharides such as gum arabic, locust bean gum, tranto gum, guar gum, and tamarind seed.

[Printing method]
The inkjet ink according to the present embodiment is not particularly limited in printing method, and can be printed using an inkjet device such as a commercially available inkjet printer. Therefore, the inkjet ink according to this embodiment has a wide range of applications and is very useful. For example, the inkjet ink according to the present embodiment can be printed with a so-called drop-on-demand inkjet device that uses a piezoelectric element (piezoelectric ceramics) as an actuator, or can be printed with another inkjet device.

Drop-on-demand ink-jet devices include, for example, devices employing a thermal ink-jet method in which ink is ejected using water vapor pressure generated by instantaneously heating minute heat-generating elements to a high temperature (200 to 300° C.), and actuators. An electrostatic type device that ejects ink jet ink by electrostatically vibrating a device, and a device that employs an ultrasonic system that utilizes the cavitation phenomenon of ultrasonic waves. In addition, if the inkjet ink according to the present embodiment has charging performance, it is possible to use an apparatus that employs a continuous jetting method (continuous method).

〔tablet〕
In this embodiment, the ink-jet ink according to this embodiment may be printed on the surface of a tablet, for example, using the printing method described above. Hereinafter, the configuration of a tablet provided with a printed image (printed portion) printed with the inkjet ink according to the embodiment will be described.
The tablet according to this embodiment is, for example, a medical tablet. Here, "medical tablets" include, for example, uncoated tablets (plain tablets), sugar-coated tablets, enteric-coated tablets, orally disintegrating tablets, etc., as well as film-coated tablets in which a water-soluble surface layer is formed on the outermost surface of the tablet. This includes locks and the like.

1(a) and 1(b) are a plan view showing a first configuration example of a medical tablet according to the present embodiment, and a cross-sectional view taken along line X1-X'1 of the plan view. The medical tablet shown in FIGS. 1(a) and 1(b) is an uncoated tablet, and an image 9 is printed on the surface of the base 1. FIG. This image 9 is an arbitrary image such as a character, a symbol, or a bar code, and is printed by an inkjet printing method using the inkjet ink described above.
2(a) and 2(b) are a plan view showing a second configuration example of a medical tablet according to the present embodiment, and a cross-sectional view taken along line X2-X'2 of the plan view. The medical tablet shown in FIGS. 2(a) and 2(b) is a film-coated tablet, and an image 9 is printed on the surface of the film 5 covering the base 1. FIG. The image 9 shown in FIGS. 2(a) and 2(b) was also printed by an inkjet printing method using the inkjet ink described above, like the image 9 shown in FIGS. 1(a) and 1(b). be.

The active ingredient contained in the medical tablet is not particularly limited. For example, substances effective in the prevention and treatment of various diseases (e.g., sleep-inducing action, tranquilizer activity, antibacterial activity, hypotensive action, anti-angina activity, analgesic action, anti-inflammatory activity, tranquilizing action, anti-diabetic activity, diuretic action) , anticholinergic activity, antihyperacid activity, antiepileptic activity, ACE inhibitory activity, β-receptor antagonist or agonist activity, narcotic activity, appetite suppressant activity, antiarrhythmic activity, antidepressant activity, anticoagulant activity, antidiarrheal activity , antihistamine activity, antimalarial activity, antitumor activity, immunosuppressive activity, antiparkinsonian activity, antipsychotic activity, antiplatelet activity, antihyperlipidemic activity, etc.), cleaning agent, perfume , substances having a deodorant action, etc., but are not limited to them.

The tablet according to the present embodiment may optionally contain an active ingredient and a carrier acceptable for its intended use. For example, in the case of medical tablets, a pharmaceutically acceptable carrier can be blended. As a pharmaceutically acceptable carrier, various organic or inorganic carrier substances commonly used as pharmaceutical materials are used, and for example, excipients, lubricants, binders, disintegrants, thickeners, etc. are appropriately blended in appropriate amounts. . Additives such as preservatives, antioxidants, coloring agents and sweeteners can also be used as necessary.

In this embodiment, a medical tablet has been described as an example of a tablet, but the present invention is not limited to this. The ink-jet ink according to the present embodiment may be printed on any surface without particular limitation, and may be printed on the surface of various tablets such as feed, fertilizer, cleaning agents, and foods such as ramune sweets. In addition, the inkjet ink according to the present embodiment is not particularly limited in the size of the object to be printed, and can be applied to tablets of various sizes. Moreover, the inkjet ink according to the present embodiment may be used for direct printing on food, and for packages that come into direct contact with pharmaceuticals and food, in addition to the above-described direct printing on the surface of tablets.

In addition, the medical tablet in the present embodiment is not particularly limited, but film-coated tablets in which the surface is coated with a film coat layer tend to be particularly effective. This is because film-coated tablets have fewer voids than uncoated tablets on the printed tablet surface, and ink tends to remain on the tablet surface. Therefore, the inkjet ink according to the present embodiment is more likely to exhibit a quick-drying effect as compared with the inkjet ink according to the conventional technology.

(Effect of this embodiment)
(1) The inkjet ink according to the present embodiment is an inkjet ink containing water, an alcohol solvent, carbon, and a dispersant, wherein the alcohol solvent contains at least one of isopropyl alcohol and normal propyl alcohol, and alcohol The concentration of the solvent is 35 parts by mass or less with respect to the entire inkjet ink, the dispersant contains a sucrose fatty acid ester having an HLB value within the range of 11 or more and 20 or less, and the content of the sucrose fatty acid ester is , within the range of 48% by mass or more and 100% by mass or less with respect to carbon.
With such a configuration, even when the amount of the alcohol solvent added to the carbon inkjet ink is increased to improve the drying property, it is possible to reduce the deterioration of the resumability of printing compared to the conventional technology. .

(2) In addition, the inkjet ink according to the present embodiment further includes a humectant, and the content of the humectant is in the range of 0.001 parts by mass or more and 20 parts by mass or less with respect to the entire inkjet ink. good too.
With such a configuration, it is possible to impart sufficient drying properties for use in inkjet inks, and to further reduce deterioration in resumability of printing.
(3) Further, the content of the wetting agent contained in the inkjet ink according to the present embodiment may be 3 parts by mass or less with respect to the entire inkjet ink.
With such a configuration, it is possible to impart sufficient drying properties to the inkjet ink, and to further reduce deterioration in resumability of printing.

(4) Further, the humectant contained in the inkjet ink according to this embodiment may contain at least one of propylene glycol and glycerin.
With such a configuration, it is possible to impart sufficient drying properties to the inkjet ink, and to further reduce deterioration in resumability of printing.
(5) The inkjet ink according to the present embodiment may further contain a binder, and the binder may contain a polysaccharide.
With such a configuration, it is possible to impart sufficient drying properties to the inkjet ink, and to further reduce deterioration in resumability of printing.

(6) In addition, the weight average molecular weight of the polysaccharide contained in the inkjet ink according to this embodiment may be in the range of 1,000 or more and less than 10,000.
With such a configuration, it is possible to impart sufficient drying properties to the inkjet ink, and to further reduce deterioration in resumability of printing.
(7) In addition, the inkjet ink according to the present embodiment may be used for direct printing on tablet surfaces, direct printing on foods, and packages that come into direct contact with pharmaceuticals and foods.
With such a configuration, direct printing on the surface of tablets and direct printing on foods are possible, and it is possible to use for packages that come into direct contact with pharmaceuticals and foods.

(8) Moreover, the tablet according to the present embodiment includes a printed image printed with the inkjet ink described above.
With such a configuration, it is possible to impart edibility even to the print image portion printed on the surface of the tablet.
(9) Further, the tablet according to the present embodiment may be a medical tablet.
With such a configuration, it is possible to impart edibility even to the printed image portion printed on the surface of the medical tablet.

[Example]
EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the Examples.
(Manufacture of inkjet ink)
The procedure for preparing the inkjet ink will be described below.
Inkjet inks contain components such as pigments, organic solvents, water, dispersants, and other optional additives. As for the order of preparation, first, water and an organic solvent were mixed to obtain a mixed solvent. Next, after adding the dispersant and the colorant to the mixed solvent, other additives were added. Finally, this mixed liquid was placed in a dispersing machine such as a paint shaker, and finely divided and dispersed for a specified period of time. Thus, an inkjet ink according to this example was prepared. Various components will be specifically described below.

Purified water (ion-exchanged water) was used as the water constituting the ink.
Ethanol, 1-propanol, and 2-propanol were used as organic solvents as dry solvents.
Propylene glycol and glycerin were used as wetting agents.
Sucrose fatty acid ester was used as a dispersant.
Maltodextrin and polydextrose were used as binders.
The above ingredients were prepared as inks in 21 different formulations. Its composition is shown in Table 1.
Solid foreign matter in the liquid was removed by passing each of the inks described above through a membrane filter. Specifically, the purified ink was obtained by passing through a membrane filter (cellulose acetate membrane) with a diameter of 5.0 μm once and then through a membrane filter (cellulose acetate membrane) with a diameter of 0.8 μm once.

The inkjet inks of Examples 1 to 14 and the inkjet inks of Comparative Examples 1 to 7 were prepared by the preparation method described above. Table 1 shows the components of the inkjet inks of Examples 1-14 and the inkjet inks of Comparative Examples 1-7. In addition, each of the inkjet inks of Examples 1 to 14 and Comparative Examples 1 to 7 was evaluated for carbon dispersion stability, drying property, and printing resumability. Table 1 shows the results of each evaluation. In addition, the evaluation method in the present example is as follows.

(1) Evaluation of Dispersion Stability Each inkjet ink of Examples 1 to 14 and Comparative Examples 1 to 7 was left at 40° C. for 14 days, and the median diameter of carbon was measured. An increase in the median diameter means that the carbon particles are agglomerated and that the dispersion stability is low. In addition, the evaluation criteria are as follows.
○: No significant change in median diameter ×: Clearly increased in diameter It means that the increase width of the median diameter after standing for 14 days is 10 nm or less. Moreover, the phrase "clearly increased in diameter" means that the increase in the median diameter exceeds 10 nm.
The dispersion stability of Examples 1 to 14 was all "Good", while the dispersion stability of Comparative Examples 1 to 3 was "Bad".

(2) Evaluation of dryness by transfer test For the following two types of tablets 1 and 2, the print resolution is 600 dpi in the main scanning direction, the sub-scanning direction (conveyance direction of recording media such as tablets) 600 dpi, and the total number of nozzles is 2,656. Using a piezoelectric ceramic-driven drop-on-demand ink jet head, each image was printed with a print drop amount of 12 pl per drop.
・Tablet 1 (film-coated tablet)
Tablet type Tablet 2 (difficult-to-print tablet) in which a coating layer is formed on the surface of a tablet by incorporating polyethylene glycol, titanium oxide pigment, etc. into hydroxypropylcellulose, hydroxypropylmethylcellulose, etc.
A tablet type in which a coating layer is formed on the surface of the tablet by adding polyethylene glycol, titanium oxide pigment, etc. to polyvinyl alcohol.

10 seconds after printing, the tablet attached to the digital force gauge was brought into contact with the printed tablet at a pressure of 2 to 3 N for 0.4 to 0.5 seconds, and it was confirmed whether the printed ink did not transfer. . In addition, in Table 1, the density of the transferred ink was visually observed as a result of evaluation of dryness. Evaluation criteria are as follows.
◎: When there is no transfer of ink ○: When the transfer of ink is very slight, and it is difficult to visually check △: When the color of the transferred ink is light, but it can be visually confirmed easily ×: When the transferred ink is dark The drying properties of Examples 1 to 14 were all "excellent" or "good", while the drying properties of Comparative Examples 4 and 5 were "poor".

(3) Evaluation of print resumability The inkjet head has a print resolution of 600 dpi in the main scanning direction, 600 dpi in the sub-scanning direction (conveyance direction of recording media such as tablets), and a drop-on-demand piezoelectric ceramic drive with a total of 2,656 nozzles. type inkjet head was used. After leaving the ink in the inkjet head for a specified time (30 to 120 minutes) without flushing, the inkjet head was used to print a test pattern with a printing drop amount of 6 pl per drop. Then, it was confirmed from the printing state of the test pattern whether or not the ink could be ejected from all the nozzles without any non-ejection amount. In addition, in Table 1, as the evaluation result of resumability of printing, the standing time during which the ink can be ejected was measured. Evaluation criteria are as follows.
◎: 60 minutes or more and less than 120 minutes ○: 30 minutes or more and less than 60 minutes ×: less than 30 minutes While the resumability of printing in Examples 1 to 14 is all "◎" or "○", Comparative Examples 6 to The resumability of printing of No. 7 was "x".

From the above results, the inkjet ink contains water, an alcohol solvent, carbon, and a dispersant, the alcohol solvent contains at least one of isopropyl alcohol and normal propyl alcohol, and the concentration of the alcohol solvent is is 35 parts by mass or less, the dispersant contains a sucrose fatty acid ester having an HLB value within the range of 11 or more and 20 or less, and the content of the sucrose fatty acid ester is 48% by mass or more to carbon and 100% by mass % or less, even when the amount of the alcohol solvent added to the carbon inkjet ink is increased to improve the drying property, the decrease in resumability of printing can be reduced compared to the conventional technology. I know you can.

1 Base 5 Film 9 Image

Claims (10)

An inkjet ink containing water, an alcohol solvent, carbon, and a dispersant,
The inkjet ink further comprises a humectant,
The alcohol solvent contains only at least one of isopropyl alcohol and normal propyl alcohol,
The content of the alcohol solvent is 35 parts by mass or less with respect to the entire inkjet ink,
The dispersant contains a sucrose fatty acid ester having an HLB value within the range of 11 or more and 20 or less,
The content of the sucrose fatty acid ester is in the range of 48% by mass or more and 100% by mass or less with respect to the carbon,
An inkjet ink, wherein the humectant contains only one of propylene glycol and glycerin. 2. The inkjet ink according to claim 1, wherein the content of the humectant is in the range of 0.001 parts by mass or more and 20 parts by mass or less based on the total amount of the inkjet ink. 3. The inkjet ink according to claim 2, wherein the content of the wetting agent is 3 parts by mass or less with respect to the entire inkjet ink. further comprising a binder;
4. The inkjet ink of any one of claims 1-3, wherein the binder comprises a polysaccharide. 5. The inkjet ink of claim 4, wherein the polysaccharide has a weight average molecular weight in the range of 1,000 to less than 10,000. 6. The inkjet ink according to any one of claims 1 to 5, which is used for direct printing on the surface of tablets, direct printing on foods, and packages that come into direct contact with pharmaceuticals and foods. further comprising a binder;
The inkjet ink of claim 1, wherein the binder comprises maltodextrin, erythritol, dextran, polydextrose, carboxymethylcellulose, hydroxymethylcellulose, or sodium alginate. further comprising a binder;
2. The inkjet ink of claim 1, wherein the binder comprises only one of maltodextrin and polydextrose. A tablet comprising a printed part printed with the inkjet ink according to any one of claims 1 to 8. 10. The tablet according to claim 9, which is a medical tablet.

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